This is very outdated information. AV1 encoding with SVT-AV1, which is a high performance encoder written by Netflix and Intel, works faster than x265 (and other h.265 encoders), and is much closer to x264 IIRC. With lower quality presets it worked at 3-4× on my old Haswell i5. On higher ones that still make sense by their own recommendations, the speed was around 1×. That CPU is over 10 years old.
Encoding video on CPU is a no-go, AV1 is only supported on Alchemist IIRC. Certainly no hardware I possess has accelerated AV1 encode. I can do HEVC at 8x, SVT-AV1 manages 0.5x for the same file. There's just no comparison.
On which preset for SVT-AV1? One of the strengths of SVT-AV1 is the presets offer a very wide trade off between quality and complexity. See the chart here:
Even using -preset 12 and it's still 8x slower than hevc_nvenc. Encoding on CPU just isn't viable, not to mention the enormous perf impact on everything else running on my computer vs next to no perf impact when I use nvenc.
AV1 is already faster and has been for around three years — if you're not using the reference encoder, which is dog slow, and that will probably not change. Have a gander at SVT-AV1.
SVT-AV1 can achieve better quality for the same encode time as x265 at every point of the encoding curve. Alternatively SVT-AV1 can achieve the same quality for better encoding time: